README.md in cousin_roman-1.0.2 vs README.md in cousin_roman-1.0.3

@@ -33,10 +33,10 @@
 'MMYUOX'.to_arabian # => nil
 'MMYOUX'.to_arabian! # => TypeError: not a valid roman number
 
 2013.to_roman # => 'MMXIII'
 '0'.to_roman # => nil
-'100500'.to_roman # => TypeError: not a valid roman number
+'100500'.to_roman! # => TypeError: not a valid roman number
 ```
 
 ## Testing
 
 Just run